- a common mineral, titanium dioxide, TiO2, usually reddish-brown in color with a brilliant metallic or adamantine luster, occurring in crystals: used to coat welding rods.
- a black, yellowish, or reddish-brown mineral, found in igneous rocks, metamorphosed limestones, and quartz veins. It is a source of titanium. Composition: titanium dioxide. Formula: TiO 2 . Crystal structure: tetragonal
